1. Technical Field
The present invention relates to a semiconductor device.
2. Related Art
FIG. 3 is a plan view showing a conventional semiconductor device. In a semiconductor device 100, dummy conductor patterns 102 are arranged in the vicinity of a high-frequency interconnect 101. The dummy conductor patterns are provided for the purpose of suppressing production of pits, called erosion, which tends to occur in the process of CMP when a pattern of an interconnect layer has dense and scarce portions. More specifically, provision of the dummy conductor patterns 102 facilitates processing of a layer containing the high-frequency interconnect 101 when the semiconductor device 100 is manufactured. The high-frequency interconnect 101 herein functions as an inductor.
Preceding technical literatures relevant to the present invention may be exemplified by Japanese Laid-Open Patent Publication No. 2001-267322, and Ali Hajimiri et al., “Design Issues in CMOS Differential LC Oscillators”, IEEE JOURNAL OF SOLID-STATE CIRCUITS, Vol. 34, No. 5, May 1999, pp. 717-724.
A problem, however, arises when high-frequency current flows through the high-frequency interconnect 101 in the semiconductor device 100 shown in FIG. 3. More specifically, eddy current may be produced in the dummy conductor pattern 102 in the vicinity of the high-frequency interconnect as shown in FIG. 4, due to a magnetic field induced around the high-frequency interconnect 101. The drawing is a plan view showing an enlarged view of the portion surrounded by the dashed line in FIG. 3. Arrow A1 in the drawing expresses the direction of current flowing through the high-frequency interconnect 101, and arrows A2 express the direction of eddy current flowing in the dummy conductor pattern 102.
When the eddy current appears in this way, another magnetic field will appear in the direction of canceling the above-described magnetic field, based on Lentz's law. Circuit constants of the high-frequency interconnect 101 may fluctuate, and as a consequence, transmission characteristics of the high-frequency interconnect 101 may fluctuate.